The present disclosure generally relates to infusion site interfaces with soft infusion cannulas and insertion devices for use with soft infusion cannulas, sensors, and the like, and, in particular, to infusion site interfaces used with infusion pumps and insertion devices for infusion site interfaces used with infusion pumps.
Devices for the automated release of liquid medicines are generally used with patients who have continuous, but varying needs, of a medicine that can be administered by subcutaneous infusion. Specific applications are, for example, certain pain therapies as well as the treatment of diabetes. Infusion pumps are particularly suitable for self-administration of liquid medicine. In such cases, computer controlled infusion pumps are used, which can be carried by on the patient's body and which contain a certain amount of liquid medicine in a medicine reservoir. The medicine reservoir often comprises medicine sufficient for one to several days. The liquid medicine is supplied to the patient's body from the medicine reservoir through an infusion cannula or an injection needle which is commonly placed in the subcutaneous body tissue.
A common type of infusion pump systems for continuous subcutaneous infusion comprises an infusion pump fluidly connected to an infusion set having an infusion site interface and infusion tubing. The infusion pump is attached to a convenient place on the patient's body, or clothes, and the infusion tubing is fluidly connected to the pump with a suitable connector. The infusion site interface is placed at a suitable position on the body, often in the abdominal region around and below the navel. Other possible infusion sites include upper leg, upper buttocks, hips, upper arms and lower back. The infusion site interface contains an infusion cannula inserted into the subcutaneous tissue of the patient. The infusion cannula can be a rigid, or semi-rigid, hollow needle or as a soft, flexible cannula, for example in the form of a PTFE cannula. Soft cannulas are generally preferred. To avoid medical problems such as infections, the infusion site interface has to be regularly replaced, usually after a few days.
Soft infusion cannulas are well known for both intravenous and subcutaneous infusion. A rigid insertion needle arranged inside the soft cannula facilitates penetration of the skin of the patient and insertion of the cannula into the body tissue. Likewise, hollow sensors for measuring an analyte such as, for example, glucose are known. After the infusion cannula, or the sensor, has been placed, the insertion needle is removed from the cannula, or sensor, while the soft cannula or sensor remains in the body tissue.
The infusion cannula can be inserted perpendicular to the body surface or at an angle. Infusion site interfaces with angled cannulas can have the advantage that the needle may be easily manually inserted in the body tissue using the same technique as for standard injection needles. Furthermore, the part of the cannula placed in the body can be longer for obtaining a certain infusion depth which can lower the risk of the cannula accidentally leaving the body tissue during movements of the patient.
FIGS. 1(a) and (b) depict an example of a known infusion site interface 1 with angled infusion cannula 12, which is similar to an infusion site interface of WO 02/07804 A1 which is hereby incorporated by reference. Another similar infusion site interface is part of an infusion set distributed by Roche Diabetes Care AG, Burgdorf, Switzerland, under the name ACCU-CHECK® TENDERLINK®.
Other types of known infusion site interfaces comprise two separate septums. One septum is used to seal closed the cavity when the insertion needle is removed from the cannula and a second septum is used to fluidly connect the cavity with infusion tubing or a pump system via a hollow needle penetrating the second septum. Generally, such arrangements are used for infusion site interfaces with cannulas that penetrate the skin perpendicularly. Thus, the first septum is arranged collinear with the perpendicular insertion needle. The second septum is arranged in a right angle to the first septum, in order to allow attaching a connecting infusion tubing horizontally, parallel to the adhesive pad and the patient's skin.
The manufacture of infusion site interfaces with two septums is typically more expensive than with one septum because the injection molding is more complicated. In addition, such interfaces have a higher overall height which increases the risk of the infusion site interface getting caught on clothes. Furthermore, the volume of the cavity in the interface may have to be larger for geometrical reasons. Volumes in the fluid path that cannot be emptied (the so-called dead volume), such as the volume of the cavity, are preferred to be as small as possible in infusion pump applications.
Many diabetic patients attach the infusion site interface and insert the infusion cannula, or sensor, themselves. However, even with extensive training, the handling of sharp, pointed needles unavoidably poses a risk of injuries for patients, as well as medical personnel. In addition, inappropriate disposal of used, and thus contaminated, insertion needles represents a health risk for third persons, for example, small children. While suitable disposable containers for used needles are generally available in medical facilities, self-care patients typically do not have them and have to dispose the insertion needle together with normal household waste.
Therefore, there is a need for devices for inserting cannulas and sensors and for interfaces having such cannulas and sensors, that allow easy and safe handling by both medical personnel and patients, and that can be safely disposed after use. Furthermore there is a need for infusion site interfaces that allow easy and safe use, have a low profile, and are less prone to accidentally catching on clothing, obstacles or the like.